Rotors are deployed, for example, in wind turbines. Here the rotors usually have a hub design. For the rotor blades a pitch angle, or blade setting angle, also designated as a pitch angle, can be altered. By this means the power absorbed by the rotor can be matched to the operating conditions (“pitch hub”). In particular, a protection from overload can be implemented in this manner Existing systems are often complicated in build and are only suitable for wind turbines above a certain size. In particular, suitable mechanisms for small wind turbines and models of wind turbines are not widely available.
In the document DE 20 2009 012 104 U1 is described a design of a small wind turbine, in which the adjustment of the pitch angle of the rotor blades is implemented utilising a slide block arranged coaxially with the hub, which is connected with the rotor blades via articulated levers. The design as embodied with linkages and rods leads to a required size for the hub, which cannot be further reduced, even for small rotors. This is a particular disadvantage if the surface area taken up by the hub is large in comparison to the whole rotor surface area. A further disadvantage is that the link rods have a negative effect on the aerodynamics of the rotor. Protective cladding (a spinner) would be the current solution to prevent this, but this reduces the effective proportion of the rotor surface area for power output.
A more compact design of a rotor with an alterable blade setting angle is described in the document EP 1 076 590 B1. In one embodiment the alteration of the blade setting angle takes place by means of the axial displacement of a means of translation; a mounting is let into the axial centre of the means of translation, as a result of which levers attached to the foot of the rotor blades are moved such that the rotor blades rotate. In this design the disadvantage is that a relatively small axial displacement of the means of translation leads to a large alteration of the blade setting angle, which in practice leads to inaccuracies in the setting of the blade setting angle. This may be acceptable for rotors of model aircraft, towards which this design of known art is particularly directed, as long as the blade setting angle is not altered during operation; instead a desired pitch angle (=pitch of the propeller) is set just once before the aircraft is operated.